package com.senseuni.da.utils;


import android.util.Base64;

import javax.crypto.Cipher;

import java.nio.charset.StandardCharsets;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

/**
 * RSA加密解密
 *
 * @author Ray
 **/
public class RsaUtils {
    // Rsa 私钥
    public static String privateKey = "";

    public static String publicKey = "";
    /**
     * 私钥解密
     * @param text             待解密的文本
     * @return 解密后的文本
     */
    public static String decryptByPrivateKey(String text) throws Exception {
        return decryptByPrivateKey(privateKey, text);
    }

    /**
     * 私钥加密
     *
     * @param text             待加密的文本
     * @return 加密后的文本
     */
    public static String encryptByPrivateKey(String text) throws Exception {
        return encryptByPrivateKey(privateKey, text);
    }

    /**
     * 公钥解密
     *
     * @param publicKeyString 公钥
     * @param text            待解密的信息
     * @return 解密后的文本
     */
    public static String decryptByPublicKey(String publicKeyString, String text) throws Exception {
        X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(Base64.decode(publicKeyString, Base64.DEFAULT));
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        cipher.init(Cipher.DECRYPT_MODE, publicKey);

        byte[] result = cipher.doFinal(Base64.decode(text, Base64.DEFAULT));
        return new String(result, StandardCharsets.UTF_8);
    }

    /**
     * 私钥加密
     *
     * @param privateKeyString 私钥
     * @param text             待加密的信息
     * @return 加密后的文本
     */
    public static String encryptByPrivateKey(String privateKeyString, String text) throws Exception {
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(Base64.decode(privateKeyString, Base64.DEFAULT));
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        byte[] result = cipher.doFinal(text.getBytes());
        return Base64.encodeToString(result, Base64.DEFAULT);
    }

    /**
     * 私钥解密
     *
     * @param privateKeyString 私钥
     * @param text             待解密的文本
     * @return 解密后的文本
     */
    public static String decryptByPrivateKey(String privateKeyString, String text) throws Exception {
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec5 = new PKCS8EncodedKeySpec(Base64.decode(privateKeyString, Base64.DEFAULT));
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec5);
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        byte[] result = cipher.doFinal(Base64.decode(text, Base64.DEFAULT));
        return new String(result);
    }

    /**
     * 公钥加密
     *
     * @param publicKeyString 公钥
     * @param text            待加密的文本
     * @return 加密后的文本
     */
    public static String encryptByPublicKey(String publicKeyString, String text) throws Exception {
        X509EncodedKeySpec x509EncodedKeySpec2 = new X509EncodedKeySpec(java.util.Base64.getDecoder().decode(publicKeyString));
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec2);
        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] result = cipher.doFinal(text.getBytes());
        return Base64.encodeToString(result, Base64.DEFAULT);
    }

    /**
     * 构建RSA密钥对
     *
     * @return 生成后的公私钥信息
     */
    public static RsaKeyPair generateKeyPair() throws NoSuchAlgorithmException {
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        keyPairGenerator.initialize(1024);
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();
        String publicKeyString = Base64.encodeToString(rsaPublicKey.getEncoded(), Base64.DEFAULT);
        String privateKeyString = Base64.encodeToString(rsaPrivateKey.getEncoded(), Base64.DEFAULT);
        return new RsaKeyPair(publicKeyString, privateKeyString);
    }

    /**
     * RSA密钥对对象
     */
    public static class RsaKeyPair {
        private final String publicKey;
        private final String privateKey;

        public RsaKeyPair(String publicKey, String privateKey) {
            this.publicKey = publicKey;
            this.privateKey = privateKey;
        }

        public String getPublicKey() {
            return publicKey;
        }

        public String getPrivateKey() {
            return privateKey;
        }
    }


    public static void main(String[] args) throws Exception{
        // 公钥加密
        String s = encryptByPublicKey(publicKey, "david123");
        System.out.println(s);
        // 私钥解密
        String s1 = decryptByPrivateKey("R1cO69lSOUQ7gAAGoWbhzGsA0bnUp+48Wd0VGdkNvvZD6dU2aUkXlKvIBF485M+W/WVDD7V4AWDT/4kKhrVMF4s8QuNkmy6WTdi/1THunnc/kh6tBCPMr5Ifk/Rl3FWf3QIRPLZTdXgYDEfcYvu/OrvhtsDwAELTDEes3MYl7j4=");
        System.out.println(s1);

        System.out.println("======================");
        String s2 = encryptByPrivateKey(privateKey, "123456");
        System.out.println(s2);
        String s3 = decryptByPublicKey(publicKey, s2);
        System.out.println(s3);
    }
}